HIGH and LOW signals on the BS2 and BS2SX
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Hi,
I would like to know if 4.42 V going into one of the I/O pins will be
read as a logic high (1). I would also like to know if 0.1 V going
into the I/O pins will be read as a logic low (0).
I would also like whether or not a negative voltage will be seen as a
ground.
I would like to know if 4.42 V going into one of the I/O pins will be
read as a logic high (1). I would also like to know if 0.1 V going
into the I/O pins will be read as a logic low (0).
I would also like whether or not a negative voltage will be seen as a
ground.
Comments
As the stamp uses TTL level logic:
a logic 0 is read whenever the input voltage is below 0.8V
a logic 1 is read whenever the input voltage is above 2.3V
a negative voltage should NEVER be supplied to any input pin
greetings peter
Oorspronkelijk bericht
Van: rpsu279@y... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oA_XVWl5WUiBH2eGF9G2pq2MTKRF3x-vBWtnSnFBE32Tkg7XGLNVvelSu4biALxqRorxFZAw9WoJ]rpsu279@y...[/url
Verzonden: zaterdag 22 september 2001 18:42
Aan: basicstamps@yahoogroups.com
Onderwerp: [noparse][[/noparse]basicstamps] HIGH and LOW signals on the BS2 and BS2SX
Hi,
I would like to know if 4.42 V going into one of the I/O pins will be
read as a logic high (1). I would also like to know if 0.1 V going
into the I/O pins will be read as a logic low (0).
I would also like whether or not a negative voltage will be seen as a
ground.
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level is read as a 1, anything below is read as 0. If you're going to have a
negative voltage (will read as 0), you should put a current limiter
(resistor) in line with the pin to keep the internal protection diodes from
burning up.
-- Jon Williams
-- Applications Engineer, Parallax
In a message dated 9/22/01 12:43:53 PM Central Daylight Time,
rpsu279@y... writes:
> I would like to know if 4.42 V going into one of the I/O pins will be
> read as a logic high (1). I would also like to know if 0.1 V going
> into the I/O pins will be read as a logic low (0).
> I would also like whether or not a negative voltage will be seen as a
>
[noparse][[/noparse]Non-text portions of this message have been removed]
>I would like to know if 4.42 V going into one of the I/O pins will be
>read as a logic high (1). I would also like to know if 0.1 V going
>into the I/O pins will be read as a logic low (0).
>I would also like whether or not a negative voltage will be seen as a
>ground.
The threshold is about 1.3 to 1.4 volts. Anything less than
threshold reads low. Anything greater reads high. A negative
voltage reads low, but be sure you have a resistor in series
sufficient to limit the current that flows through the protection
diodes.
-- Tracy
logical 0, anything above is a logical 1. Best not to exceed the input
voltage limits on the pins.
Original Message
> I would like to know if 4.42 V going into one of the I/O pins will be
> read as a logic high (1). I would also like to know if 0.1 V going
> into the I/O pins will be read as a logic low (0).
> I would also like whether or not a negative voltage will be seen as a
> ground.
> threshold reads low. Anything greater reads high. A negative
> voltage reads low, but be sure you have a resistor in series
> sufficient to limit the current that flows through the protection
> diodes.
I had my students run an experiment last year. They set up a
voltage divider on a BOE board and fed the voltage into a I/O pin.
They downloaded a program that just debuged the state of the pin
while they slowly tweaked the pot. The average fo the class was
1.42 volts. Neat experiment, but the students have to be patient.
Paul